Source : Webster's Revised Unabridged Dictionary (1913)

Bell pepper \Bell" pep`per\ (Bot.)
   A species of Capsicum, or Guinea pepper ({C. annuum}). It is
   the red pepper of the gardens.

Capsicum \Cap"si*cum\ (k[a^]p"s[i^]*k[u^]m), n. [NL., fr. L.
   capsa box, chest.] (Bot.)
   A genus of plants of many species, producing capsules or dry
   berries of various forms, which have an exceedingly pungent,
   biting taste, and when ground form the red or Cayenne pepper
   of commerce. [1913 Webster]

   Note: The most important species are {Capsicum baccatum} or
         bird pepper, {C. fastigiatum} or chili pepper, {C.
         frutescens} or spur pepper, and {C. annuum} or Guinea
         pepper, which includes the bell pepper and other common
         garden varieties. The fruit is much used, both in its
         green and ripe state, in pickles and in cookery. See
         {Cayenne pepper}. [1913 Webster]

Cayenne \Cay*enne\, n. [From Cayenne, a town and island in
   French Guiana, South America.]
   Cayenne pepper.

   {Cayenne pepper}.
   (a) (Bot.) A species of {Capsicum} ({C. frutescens}) with
       small and intensely pungent fruit.
   (b) A very pungent spice made by drying and grinding the
       fruits or seeds of several species of the genus
       {Capsicum}, esp. {C. annuum} and {C. Frutescens}; --
       called also {red pepper}. It is used chiefly as a
       condiment.